//
//  Common.hpp
//  ConcurrentMemoryPool
//
//  Created by 张木林 on 5/3/25.
//

#pragma once

#include <iostream>
#include <vector>
#include <algorithm>

#include <time.h>
#include <unordered_map>
#include <map>
#include <assert.h>

#include <thread>
#include <mutex>
#include <cstddef>
#include <stdexcept>

using std::cout;
using std::endl;

#if defined(_WIN32) || defined(_WIN64)
    #include <windows.h>
#else

 //mac平台需要的头文件
#include<unistd.h> //getpagesize
#include<pthread.h>
#include<sys/mman.h> //mmap

#endif

static const size_t MAX_BYTES = 256 * 1024;
static const size_t NFREELIST = 208;
static const size_t NPAGES = 129;
static const size_t PAGE_SHIFT = 13;




// 直接去堆上按页申请空间
#ifdef _WIN64
typedef unsigned long long PAGE_ID;

#elif _WIN32
typedef size_t PAGE_ID;

#else
typedef size_t PAGE_ID;

#endif



inline static void* SystemAlloc(size_t kpage)
{
    void* ptr = nullptr;
    
#ifdef _WIN32
    ptr = VirtualAlloc(0,kaage<<13,MEM_COMMIT | MEM_RESERVE,PAGE_READWRITE);
#else
    size_t size = kpage<<13;
    ptr = mmap(nullptr,size,PROT_READ|PROT_WRITE,MAP_PRIVATE| MAP_ANONYMOUS, -1, 0);
    if(ptr == MAP_FAILED)
    {
        ptr = nullptr;
    }
#endif
    if(ptr == nullptr)
    
        throw std::bad_alloc();
        return ptr;
    
}
static void*& NextObj(void* obj)
{
    return *(void**)obj;
}


// 管理切分好的小对象的自由链表
class FreeList
{
public:
    void Push(void* obj)
    {
        assert(obj);

        // 头插
        //*(void**)obj = _freeList;
        NextObj(obj) = _freeList;
        _freeList = obj;
        ++_size;
    }

    void PushRange(void* start, void* end,size_t n)
    {
        NextObj(end) = _freeList;
        _freeList = start;
        
        _size += n;
    }
    
    
    void PopRange(void*& start,void*& end,size_t n)
    {
        assert(n<=_size);
        start = _freeList;
        end = start;
        
        for(size_t i = 0;i<n-1;++i)
        {
            end = NextObj(end);
        }
        _freeList = NextObj(end);
        NextObj(end) = nullptr;
        _size -= n;
    }

    void* Pop()
    {
        assert(_freeList);

        // 头删
        void* obj = _freeList;
        _freeList = NextObj(obj);

        return obj;
    }

    bool Empty()
    {
        return _freeList == nullptr;
    }

    size_t& MaxSize()
    {
        return _maxSize;
    }
    
    size_t Size()
    {
        return _size;
    }

private:
    void* _freeList = nullptr;
    size_t _maxSize = 1;
    size_t _size = 0;
};

// 计算对象大小的对齐映射规则
class SizeClass
{
public:
    // 整体控制在最多10%左右的内碎片浪费
    // [1,128]                    8byte对齐        freelist[0,16)
    // [128+1,1024]                16byte对齐        freelist[16,72)
    // [1024+1,8*1024]            128byte对齐        freelist[72,128)
    // [8*1024+1,64*1024]        1024byte对齐     freelist[128,184)
    // [64*1024+1,256*1024]        8*1024byte对齐   freelist[184,208)

    /*size_t _RoundUp(size_t size, size_t alignNum)
    {
        size_t alignSize;
        if (size % alignNum != 0)
        {
            alignSize = (size / alignNum + 1)*alignNum;
        }
        else
        {
            alignSize = size;
        }

        return alignSize;
    }*/
    // 1-8
    static inline size_t _RoundUp(size_t bytes, size_t alignNum)
    {
        return ((bytes + alignNum - 1) & ~(alignNum - 1));
    }

    static inline size_t RoundUp(size_t size)
    {
        if (size <= 128)
        {
            return _RoundUp(size, 8);
        }
        else if (size <= 1024)
        {
            return _RoundUp(size, 16);
        }
        else if (size <= 8*1024)
        {
            return _RoundUp(size, 128);
        }
        else if (size <= 64*1024)
        {
            return _RoundUp(size, 1024);
        }
        else if (size <= 256 * 1024)
        {
            return _RoundUp(size, 8*1024);
        }
        else
        {
            assert(false);
            return -1;
        }
    }

    /*size_t _Index(size_t bytes, size_t alignNum)
    {
    if (bytes % alignNum == 0)
    {
    return bytes / alignNum - 1;
    }
    else
    {
    return bytes / alignNum;
    }
    }*/

    // 1 + 7  8
    // 2      9
    // ...
    // 8      15
    
    // 9 + 7 16
    // 10
    // ...
    // 16    23
    static inline size_t _Index(size_t bytes, size_t align_shift)
    {
        return ((bytes + (1 << align_shift) - 1) >> align_shift) - 1;
    }

    // 计算映射的哪一个自由链表桶
    static inline size_t Index(size_t bytes)
    {
        assert(bytes <= MAX_BYTES);

        // 每个区间有多少个链
        static int group_array[4] = { 16, 56, 56, 56 };
        if (bytes <= 128){
            return _Index(bytes, 3);
        }
        else if (bytes <= 1024){
            return _Index(bytes - 128, 4) + group_array[0];
        }
        else if (bytes <= 8 * 1024){
            return _Index(bytes - 1024, 7) + group_array[1] + group_array[0];
        }
        else if (bytes <= 64 * 1024){
            return _Index(bytes - 8 * 1024, 10) + group_array[2] + group_array[1] + group_array[0];
        }
        else if (bytes <= 256 * 1024){
            return _Index(bytes - 64 * 1024, 13) + group_array[3] + group_array[2] + group_array[1] + group_array[0];
        }
        else{
            assert(false);
        }

        return -1;
    }

    // 一次thread cache从中心缓存获取多少个
    static size_t NumMoveSize(size_t size)
    {
        assert(size > 0);

        // [2, 512]，一次批量移动多少个对象的(慢启动)上限值
        // 小对象一次批量上限高
        // 小对象一次批量上限低
        int num = MAX_BYTES / size;
        if (num < 2)
            num = 2;

        if (num > 512)
            num = 512;

        return num;
    }

    // 计算一次向系统获取几个页
    // 单个对象 8byte
    // ...
    // 单个对象 256KB
    static size_t NumMovePage(size_t size)
    {
        size_t num = NumMoveSize(size);
        size_t npage = num*size;

        npage >>= PAGE_SHIFT;
        if (npage == 0)
            npage = 1;

        return npage;
    }
};

// 管理多个连续页大块内存跨度结构
struct Span
{
    PAGE_ID _pageId = 0; // 大块内存起始页的页号
    size_t  _n = 0;      // 页的数量

    Span* _next = nullptr;    // 双向链表的结构
    Span* _prev = nullptr;

    size_t _useCount = 0; // 切好小块内存，被分配给thread cache的计数
    void* _freeList = nullptr;  // 切好的小块内存的自由链表
    
    //检查是否在使用
    bool _isUse = false; //
};

// 带头双向循环链表
class SpanList
{
public:
    SpanList()
    {
        _head = new Span;
        _head->_next = _head;
        _head->_prev = _head;
    }

    Span* Begin()
    {
        return _head->_next;
    }

    Span* End()
    {
        return _head;
    }

    bool Empty()
    {
        return _head->_next == _head;
    }

    void PushFront(Span* span)
    {
        Insert(Begin(), span);
    }

    Span* PopFront()
    {
        Span* front = _head->_next;
        Erase(front);
        return front;
    }

    void Insert(Span* pos, Span* newSpan)
    {
        assert(pos);
        assert(newSpan);

        Span* prev = pos->_prev;
        // prev newspan pos
        prev->_next = newSpan;
        newSpan->_prev = prev;
        newSpan->_next = pos;
        pos->_prev = newSpan;
    }

    void Erase(Span* pos)
    {
        assert(pos);
        assert(pos != _head);

        Span* prev = pos->_prev;
        Span* next = pos->_next;

        prev->_next = next;
        next->_prev = prev;
    }

private:
    Span* _head;
public:
    std::mutex _mtx; // 桶锁
};
